It is known to digitize analog audio signals received from an input transducer. It is also known to provide adjustable input impedances and adjustable gain stages in order to correctly match the transducer to the input electronics of an amplifier and to provide the required level for an analog to digital converter. However, in known systems, it is necessary for manual switches to be adjusted and possibly other manual modifications to be made in order to achieve a correct set up. Such an approach is not consistent with the trend towards producing sealed units and removing set up procedures that may require assistance from a trained technician.
It is also known for amplifiers to be provided with heat sinks and cooling vents such that any area of the amplifier that is likely to get hot, such as a board for the power amplifying components, can be cooled; such that under load, the temperature of the amplifying components remains within operational limits.
A recent trend has been towards packaging electronic components within sealed units and providing graphical user input displays for effecting control. This does not create a problem in relatively low power environments but problems in terms of controlling temperature are created in systems where the degree of amplification is substantially larger.